<!DOCTYPE html>
<html>
<head>
	<meta http-equiv="Content-Type" content="text/html">
	<meta charset="utf-8" />
	<meta http-equiv="X-UA-Compatible" content="IE=edge" />
	<meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1,maximum-scale=1,user-scalable=no" />
	<title></title>
</head>
<body erke-hide>
</body>
<script>
/**
 * @param {number} num
 * @return {string}
 */
var convertToBase7 = function(num) {
	var res=[];
	var sum=Math.abs(num);
    while(sum/7){
    	res.unshift(sum%7);
    	sum=parseInt(sum/7);
    };
    if(res.length==0){
      res=[0];  
    };
    if(num<0){
      res.unshift('-');
    };
    console.log(res.join(''));
    return res.join('');
};
var res=new convertToBase7(-8);
</script>
</html>